Heterologous expression of Thermomyces lanuginosus lipase in Aspergillus niger: stress resistance, optimization of fermentation conditions, and transcriptomic analysis

Aspergillus niger serves as a cell factory for efficient enzyme production. The lipase derived from Thermomyces lanuginosus (TLL) is known for its remarkable thermal stability and is extensively utilized in various industrial fields. In this study, a heterologous expression strain, ΔAnTll-11, of TLL was successfully constructed in A. niger. Through fermentation optimization, the lipase activity was enhanced 8.7-fold to 4547.95 U/mL, compared with the initial value of 520 U/mL. Enzymatic characterization indicated that the recombinant lipase exhibited optimum activity at pH 9.5 and 45 °C, and its activity was positively influenced by Ca²⁺, Ag⁺, Mg²⁺, and Cu²⁺. The ΔAnTll-11 strain exhibited enhanced tolerance to high osmolarity, oxidative stress, and thermal shock. Furthermore, transcriptomic analysis of the ΔAnTll-11 strain revealed that half of the total annotated genes (7199 genes) were differentially expressed genes (DEGs). According to protein‒protein interaction network and weighted gene coexpression network analyses, genes involved in ribosome function, amino acid metabolism, glycosylation, energy metabolism, and the MAPK signalling pathway may affect the expression of lipase. The transcriptomic findings elucidated the regulatory mechanisms by which A. niger expresses foreign proteins and enzymes, establishing a groundwork for further enhancing A. niger as a cell factory for efficient enzyme and protein production.